Mixing amplifiers, particularly portable mixing amplifiers, live performances, generally have a plurality of signal inputs for electrical audio signals, e.g. audio signals for microphones and electric or electro-acoustic instruments, and also outputs for connecting loudspeakers. The user can use appropriate operator control elements, e.g. rotary potentiometers, sliding potentiometers and pushbutton keys, to amplify the individual input channels in a specific way and to adjust further functions, such as signal shaping and special functions such as mono, single, etc., and to put the output signal onto output channels. The operator control elements are generally mounted on a combined display and operator control device which is arranged on the front of the mixing amplifier, for example.
The operator control elements are provided with display panels for visually displaying the status of the operator control elements, e.g. set or unset, and possibly for showing signal levels. The display panels provided are particularly LEDs, which may be arranged next to the respective operator control elements, for example.
To this end, the LEDs are generally mounted on the front panel, which forms the exterior termination of the mixing amplifier, with the front panel containing exit points or apertures for the different operator control elements. The LEDs are actuated via a circuit carrier, e.g. a board having appropriate electrical and electronic components. The circuit carrier is generally provided at a distance behind the front panel, so that an interspace is formed. For the purposes of contact connection, wires are routed from the printed circuit board through the interspace to the LEDs.
The plastic bodies of these LEDs are generally colored in the color in which the LEDs are intended to appear. This color generally does not match the general color scheme of the front panel, so that the LEDs which are off can be identified on the front panel or the user interface thereof.
The level structure of the LEDs is uneven on account of manufacture-related tolerances, which the user can identify when they are mounted on the front panel, since the LEDs are not evenly flush and the fronts of said LEDs do not describe a common vertical plane.
To ensure the desired distance between the board and the front panel, individual spacers are inserted, for example, the handling of which is therefore linked to a certain degree of assembly complexity.
For safe transport during the production process, a particular safeguard is generally required, particularly on account of the sensitivity of the wire connections, and also for the purpose of securely fixing the front panel relative to the board.
WO 2007/110576 A1 describes a mixing console for musical applications which has an input/output interface with different channels. In this case, displays or display panels are provided for showing desired information. In addition, the buttons to be pushed by the user have light sources arranged in them in order to display their activated state.
Although such mounting of light sources in the pushbuttons allows direct visual association and rapid identifiability for the user, the contact connection for the light sources is exposed to the mechanical stresses during adjustment, which means that fractures in the contact connection and similar problems can arise, for example.